How do i adjust Speedo for tire size ? 2012 Mustang GT M6

[bluegoat06]

This is all I see that pertains to speedo calibration, I'm going to go with a 275/40/19, how do I correct the speedo for the new rear tire ?
speedo by SilverFJ RSM, on Flickr

For what I've seeing I need to disable VID, change the gear to 3.73, but I thought I was supposed to see a circumference diameter ?

Thanks a lot.

[txcharlie]

You should disable VID, put in you gear ratio, under Final Drive, and VSS Tire Revs Per mile, under Sensor Calibration. It doesn't use circumference, you will use revolutions per mile. You will need to look up the specs for your tire for your specific manufacture to find the revolutions per mile.

This is a good place to start: http://tire-size-conversion.com/tire...7X13.50R20.htm

[bluegoat06]

Thanks a lot Charlie.